1. Field of the Invention
The present invention relates to a low-current female socket of the modular jack type, such as a telephone or computer female socket for connecting a computer or telephone cable of a particular device to a computer or telephone network.
2. Description of the Prior Art
An RJ 45 computer female socket generally has an insulative material body with a female entry mouth adapted to receive an RJ 45 male plug and a series of eight aligned metal contacts, with each metal contact extending freely from a tail at the female entry mouth end and having a contact part adapted to make electrical contact with a metal contact of the male plug.
The eight contacts are connected in pairs to pairs of electrical wires, each of which pairs forms a single electrical circuit.
In some countries, telephone female sockets comprise only four or six metal contacts in an insulative material body of the same type as the computer female socket described above (RJ 11 or RJ 12 female socket).
They are then adapted to receive an RJ 11 or RJ 12 male plug with four or six metal contacts.
Also, in these countries, telephone and computer installations of open-plan or modular offices often use only RJ 45 computer female sockets with eight metal contacts to transmit computer data and telephone data.
In this case, RJ 11 or RJ 12 telephone male plugs, which are narrower than RJ 45 computer male plugs, are inserted into RJ 45 computer female sockets, of which only four or six metal contacts are used.
However, if an RJ 11 or RJ 12 male plug is inserted into an RJ 45 female socket, its insulative body crushes the metal contacts at the end of the RJ 45 female socket, which are not used, and are therefore subjected to high deformation stresses.
Although the metal contacts of RJ 45 female sockets have electrically deformable branches, it often happens that when an RJ 11 or RJ 12 male plug is inserted into an RJ 45 female socket these end metal contacts exceed their elastic limit and therefore become unusable with an RJ 45 male plug.
Also, when transmitting high-frequency signals, crosstalk can occur between the various pairs of metal contacts of an RJ 45 low-current female socket in contact with the corresponding metal pairs of the RJ 45 male plug.
Crosstalk degrades message transmission and increases with the operating frequency of the computer female sockets.
Crosstalk is favored by the proximity of parallel lengths of metal contacts, since the phenomenon is due to an induced current. The critical pairs of metal contacts are usually the central pairs of metal contacts, one of which comprises contacts 3 and 6 and the other of which comprises contacts 4 and 5. In these pairs of metal contacts, each metal contact is between other metal contacts.
There are various prior art solutions to the problem of crosstalk.
One solution is to cross the metal contacts concerned over at particular locations to create an induced current with the opposite phase to cancel the induced current that causes crosstalk when transmitting high-frequency signals.
Another prior art solution is to reduce the parallel lengths of the metal contacts.
Finally, a further prior art solution is to provide appropriate compensation circuits on a printed circuit card in the low-current female socket.
In order to alleviate all of the drawbacks previously referred to, the present invention proposes a new low-current female socket of the modular jack type adapted to be used with a male plug with eight, six or four metal contacts without damaging the end metal contacts, and which offers good performance in terms of transmission of high-frequency signals.
The present invention provides a low-current female socket of the modular jack type comprising an insulative material body having a female entry mouth adapted to receive a male plug and a series of eight aligned metal contacts, each metal contact having a tail and a contact part which extends in said female entry mouth and which is adapted to make electrical contact with a metal contact of the male plug, wherein the central four metal contacts of the series, forming two pairs of contacts connected to respective pairs of electrical wires, are shorter contacts that follow a one-way path from their tail, with the contact parts thereof parallel to each other and oriented generally toward the front of the female entry mouth, and the two metal contacts at the two ends of the series are longer contacts that follow a path with portions in two opposite directions and whose contact parts are oriented generally toward the rear of the female entry mouth.
Accordingly, the end two metal contacts of the low-current female socket according to the invention are able to withstand the considerable elastic deformation caused by inserting into the female entry mouth of the female socket an RJ 11 or RJ 12 male plug, and the four central metal contacts of the low-current female socket are short, which improves the quality of transmission of high-frequency signals by minimizing the induced current.
Other non-limiting and advantageous features of the present invention are as follows:
the two pairs of end metal contacts, each adapted to be connected to a pair of electrical wires, are pairs of longer contacts that follow a path with portions in two opposite directions and whose contact parts are parallel to each other and oriented generally toward the rear of the female entry mouth;
each contact part of each longer contact of the series has one end free of any mechanical interengagement with any insulative support;
each end metal contact has the general shape of a hairpin with two different length branches connected together by a connection forming a hinge, the shorter branch is oriented toward the rear of the female entry mouth and constitutes the contact part, and the longer branch is situated to the rear of the shorter branch;
the contact part of each end metal contact is bent toward the rear of the female entry mouth;
the contact parts of the central metal contacts have at their end a beak adapted to bear against an insulative support;
the contact parts of the central metal contacts are crenellated;
the contact part of each end metal contact is shorter than the contact part of each central metal contact;
the contact parts of the central metal contacts are all the same length and the contact parts of the end metal contacts are all the same length;
the metal contacts are attached to an insulative plate and the tails of the metal contacts emerge from the insulative plate toward the rear of the body and are pinhead-shaped so that they can be force-fitted into orifices in a printed circuit support plate;
the tails of the metal contacts are arranged in a quincunx on the insulative plate and each central metal contact has a part for taking up play between its tail and its contact part; and
the female socket further includes an insulative support with eight slots adapted to receive the metal contacts and to be received in an opening at the rear of the body.
The following description with reference to the accompanying drawings, which are provided by way of non-limiting example only, explain in what the invention consists and how it can be put into effect.